KR101071899B1 - Method and energy efficient ethernet physical layer device for doing energy efficient ethernet - Google Patents

Abstract

A system and method are provided for enabling legacy media access control (MAC) to perform energy efficient ethernet (EEE). A backpressure mechanism is included in the EEE enhanced PHY that corresponds to the detected needs for switching between the various power modes of the EEE enhanced PHY. Through the back pressure mechanism, the EEE enhanced PHY may instruct the legacy MAC that transmission of data will be delayed due to an energy savings initiative within the EEE enhanced PHY.

Description

Energy Efficient Ethernet Method and Energy Efficient Ethernet Physical Layer Device for the Field {METHOD AND ENERGY EFFICIENT ETHERNET PHYSICAL LAYER DEVICE FOR DOING ENERGY EFFICIENT ETHERNET}

TECHNICAL FIELD The present invention relates generally to Ethernet systems, and more particularly, to a system and method for enabling legacy media access control to perform energy efficient ethernet (EEE).

Energy costs are on the rise in recent years. As a result, many industries have become increasingly sensitive to the impact of rising costs. One area that has attracted a lot of attention is IT infrastructure. Many companies are now investigating the power usage of their IT systems to determine whether energy costs can be reduced. For this reason, an industry focus has been placed on energy efficient networks to address the rising costs of using IT equipment (eg, PCs, display devices, printers, servers, network equipment).

When designing an energy efficient solution, one of the things to consider is the traffic profile on the network link. For example, many network links are typically in an idle state between sporadic bursts of data. On the other hand, in other network links having bursts of high-bandwidth traffic, it may be regular or intermittent low-bandwidth traffic. A further consideration for energy efficient solutions is the extent to which traffic is buffered and latency sensitive. For example, some traffic patterns (eg, HPC clusters or high-end 24-hour data centers) are very sensitive to latency, which can cause buffering problems. For this or that reason, applying energy efficient concepts to different traffic profiles can lead to different solutions. Thus, these various solutions are application dependent per se and strive to adapt the link, link rate and layers on the link to the optimal solution based on various energy costs and traffic impact.

As will be appreciated, energy efficient ethernet (EEE) solutions typically require coordination between the various layers. For example, an EEE mechanism can be implemented to transition the PHY between various energy states in a physical layer device (PHY). In supporting these various PHY energy states, the MAC and higher layers (silicon, software and firmware) need to control their operation. Ideally, a MAC-containing device may be enhanced to suit such an EEE mechanism. Otherwise, any PHY innovation for EEE will be useless in systems that include legacy MAC silicon. Thus, a mechanism is needed to allow legacy MACs to collaborate with the EEE enabled PHY.

SUMMARY OF THE INVENTION The present invention has been devised by this need, and the problem to be solved by the present invention is to provide a system and method for enabling legacy media access control for energy efficient Ethernet.

According to one aspect of the invention, the energy efficient Ethernet method in the physical layer device,

Detecting the need for transition of the physical layer between different power consumption modes;

Generating a pause frame in the physical layer device corresponding to the switching between different power consumption modes; And

And transmitting the generated pause frame from the physical layer device to a media access control device. Here, the generated pause frame instructs the medium access control device to reduce the amount of traffic sent to the physical layer device to be suitable for the switching in the physical layer device.

Preferably, the transition is a transition to a low power idle mode.

Preferably, the switch is a switch to a subset physical layer device mode.

Advantageously, said physical layer device is a backplane device.

Preferably, the physical layer device is a twisted pair device.

Advantageously, said detecting step comprises monitoring a traffic queue.

Advantageously, said detecting step comprises monitoring a subsystem status.

Preferably, the transition is part of a symmetrical transition for both directions of the link.

Preferably, the transition is part of an asymmetrical transition to one direction of the link.

According to one aspect of the invention, the energy-efficient Ethernet method for coupling the enhanced physical layer device to the legacy media access control device,

Detecting a need for transitioning the enhanced physical layer device to a low power consumption mode; And

Reducing the traffic flow from the legacy media access control device to the enhanced physical layer device in response to the detected need, wherein the reducing step comprises backpressure supported by the legacy media access control device. Signaling using a control mechanism.

Advantageously, said signaling comprises transmitting a pause frame.

Advantageously, said detecting comprises monitoring a traffic queue.

Advantageously, said detecting comprises monitoring a subsystem status.

Advantageously, said signaling is not based on direct traffic measurement.

Advantageously, said signaling is not based on a command from a peer device.

Advantageously, said back pressure control mechanism comprises an on-chip memory buffer.

According to one aspect of the invention, the energy efficient Ethernet physical layer device coupled to the medium connection control device,

A control module for generating a control signal in response to a need for switching the physical layer device to a low power consumption mode; And

And a pose generation module coupled to the control module. The pose generation module generates a pose frame according to the generated control signal, and the pose generation module generates the pose frame to reduce the inflow of the traffic from the legacy medium access control device to the physical layer device. It transmits to the said medium connection control apparatus.

Preferably, the pose generation module is implemented in hardware.

Advantageously, said pose generation module is implemented in software.

Preferably, the control module generates a control signal corresponding to the low power idle mode switch.

Advantageously, said control module generates a control signal in response to mode switching of the subset physical layer device.

Advantageously, the apparatus further comprises a buffer memory for storing traffic received from said medium access control apparatus.

Advantageously, the apparatus further comprises a buffer memory for storing the traffic received from the remote side.

BRIEF DESCRIPTION OF DRAWINGS To describe the above-described manner and other advantages and features of the present invention that can be obtained, a more detailed description of the invention briefly described above will appear with reference to specific embodiments illustrated in the accompanying drawings. It is to be understood that these drawings are merely illustrative of specific embodiments of the invention and are not intended to limit the scope thereof, and the invention will be described and described in detail and in detail through use of the accompanying drawings.

The present invention can provide a system and method for enabling legacy media access control to perform energy efficient Ethernet.

A system and method for enabling legacy media access control to perform Energy Efficient Ethernet (EEE) will be substantially shown or described in connection with at least one of the drawings and will be more fully deployed in the claims.

Various embodiments of the invention are described in detail below. While specific embodiments will be described, it will be understood that they are used for purposes of illustration only. Those skilled in the art will appreciate that other components and configurations may be used without departing from the spirit and scope of the invention.

Ethernet is being applied in a variety of environments (eg, twisted pairs, backplanes, etc.) and is becoming an increasingly convincing technology. The IEEE 802.3az energy efficient ethernet (EEE) is evaluating various ways to reduce the energy used during periods of low link utilization. In this process, a protocol may be defined that facilitates the transition from / to low power consumption modes according to changes in network requirements.

In general, a reduction in the link rate for the sub-rate of the main rate enables a reduction in power, thereby resulting in energy savings. As an example, this sub-rate can be zero rate, which produces maximum power savings.

One example of subrating is through the use of a subset PHY technique. In this subset PHY scheme, the low link usage period may be adapted by converting the PHY to a PHY at a low link rate enabled by a subset of the parent PHY. In one embodiment, the subset PHY technique may be enabled by turning off portions of the parent PHY to enable operation at low or subset rates. For example, a subset 1G PHY may be created from the parent 10GBASE-T PHY by turning off three of the four channels. In another embodiment of the present invention, the subset PHY technique can be enabled by lowering the clock rate of the parent PHY. For example, a parent PHY with an enhanced core that can be slowed down or accelerated by a frequency multiple can be lowered by a factor of 10 during low link usage, and then burst of data. The speed can be increased by factor 10 when is received. In the example of factor 10, the 10G enhancement core may transition low to the 1G link when idle, and speed up again at the 10G link rate when data is transmitted.

Another example of subrating is through the use of a low power idle (LPI) technique. In general, LPI relies on changing an active channel to a silent state when not transmitting. Energy is thereby saved when the link is off. Refresh signals may be sent periodically to enable from sleep mode to wakeup. In one embodiment, on interfaces (ie, medium dependent interface (MDI) and PHY / MAC interface) to enable fast wakeup from sleep mode and to maintain a frequency lock. A synchronization signal can be used. For example, on an MDI interface for 10GBASE-T, a simple PAM2 pseudorandom bit sequence may be used on pair A during LPI mode. This does not significantly increase the power consumed. In general, subset and LPI techniques include turning off or otherwise modifying portions of a PHY during a period of low link usage.

Regardless of the specific low power consumption modes supported by the EEE PHY, the combination of legacy MAC and EEE PHY renders the EEE mechanism within the PHY unavailable. Therefore, it is desirable to be able to reuse existing MAC devices with a new EEE PHY in a manner that does not defeat the functionality of the EEE PHY.

This feature of the invention is particularly valuable when considering the large market of controller or switch chips with MAC, or legacy chips that include MAC and PHY but allow external PHY connections. In this environment, external EEE PHYs can be coupled to existing legacy MACs. By introducing a mechanism that allows the EEE PHY function to work with legacy MAC devices, EEE benefits can be added to existing legacy devices without requiring overhaul of the entire devices.

In order to save energy, the capacity of the link is reduced. When the PHY is in a low energy state, the layers above the PHY still have the capability to burst at the maximum rate negotiated at the beginning of the connection. Once the MAC and higher layers are EEE enabled, the subsystems on the PHY will include enough buffering to allow the link to recover at the initial rate. However, in legacy systems that are not EEE-enabled, the subsystems above the PHY cannot use that memory in real time even if there is memory.

According to the invention, MAC-containing devices (eg network switches, controllers, etc.) may be enhanced to suit the EEE mechanism. In one embodiment, a backpressure mechanism is introduced to cause the legacy MAC to postpone transmission when the PHY is in a low power state or when the PHY comes out of the low power state. Specifically, the buffering system in the backpressure mechanism can be used by the EEE control policy to trigger a transition into and out of the various energy states. In fact, a feature of the present invention allows the chip memory typically used for pause frames to be reused, not only eliminating the need for additional memory for the EEE required for buffering during switching between energy states. This is to support EEE control policies.

1 is an example of a MAC-containing device implemented as a controller. In various examples, the controller may be a client (eg, laptop, desktop or workstation), server (eg, audio-video server, high performance computing (HPC) server), or consumer end device (eg, HDTV, Bluray). Etc.). As shown, the host system 130 is connected to the integrated Ethernet controller 110. The Ethernet controller 110 further includes a PHY 111, which is coupled to the MAC 112. In the example shown, MAC 112 is coupled to PCI Express device 116 via memory controller 113, and buffers 114 and processor 115 are also coupled to memory controller 113.

2 shows another example of a MAC containing device implemented as a network switch. In various examples, switching system 200 may represent a router or any other device having multi-port switching functionality. In various examples, the switch can be a consumer, SMB, enterprise, city, or access switch. In another example, switching system 200 may represent a voice of IP (VoIP) chip having a network interface (port 0) and a PC interface (port 1). In another example, however, the switching system 200 is in a service provider access network having an optical central office facing interface (port 0) and multiple interfaces facing the home and / or gateway (port 1-N). May represent a customer premise equipment (CPE) device (eg, the CPE may simply be part of a media converter and / or home gateway). The switching system 200 may also represent an access point, such as a WLAN base station. .

As shown, the switching system 200 may support an internal port and a plurality of external ports (ports 0-N) via the MAC and PHY interfaces. As will be appreciated, support for internal ports is up to the implementation. For example, a VoIP phone may include internal ports while no switch box. In addition, as shown in FIG. 2, the switch 210 may be supported by the buffers 220 and the control 230.

As shown, the PHYs of FIGS. 1 and 2 are enhanced EEE PHY devices. These enhanced EEE PHY devices may be integrated into existing integrated Ethernet controller 110 or switching system 200. From a system point of view, it is desirable to re-qualify an enhanced EEE PHY device that is familiar with its associated software, as compared to re-qualifying an entirely new chipset. For this reason, it is desirable to reuse existing MAC devices with enhanced EEE PHY devices. As noted, this scenario represents a large part of today's MAC-containing device market.

In accordance with the present invention, existing MAC devices may be reused with enhanced EEE PHYs by including the capability to create pause frames within the EEE enhanced PHYs that may be passed up to the controlling MAC of that PHY. Can be. To illustrate the features of the invention, reference is made to the example environment of FIG. 3.

As shown in FIG. 3, server 310 is in communication with switch 320 via enhanced EEE PHYs. The enhanced EEE PHY in the server 310 here includes a pause circuit 312 designed to create pause frames and send them to the MAC in the server 310.

Here, conventional systems typically transmit pause frames generated by a far end device (remote / link partner), such as switch 320. For example, this requires a request from the switch 320 to the server 310 over the link, which, when the receive buffer in the switch 320 is full, thereby requests that the server 310 pause additional transmissions. It is a situation. In the present invention, pause frames are generated by the enhanced EEE PHY in the same device on the same side of link where the transmissions are searched for to be paused. Importantly, the generation of the pause frames may be caused by an EEE control policy. One of the advantages of using pose frames is that the pose frames enter a system that buffers for the pose, which is much larger than anything that can be introduced into the PHY.

As further shown in FIG. 3, the pause frame is sent to the MAC by the pause circuit 312 within the server 310. This pause frame is used in the back pressure mechanism in server 310. This back pressure mechanism is facilitated by flow control 314 in the MAC. Upon receiving the pause frame, flow control 314 stops further transmission until release of pause timer 316. Suspension of further transmission causes traffic to accumulate in the buffers in server 310.

In one embodiment, pause timer 316 may be set to the value indicated by the pause frame, thereby suspending transmission for a specific period of time. For an EEE PHY entering or leaving a low power consumption mode, a specific time period sufficient to support a transition between two different PHY energy states can be defined. In one example, the specific time period may cause the device to resynchronize / retrain itself upon returning from the low power consumption mode. In one embodiment, the suspended transmission may resume upon receiving a pause 0 frame.

As mentioned, the generation of a pause frame by the pause circuit 312 takes place by an EEE control policy. As shown in FIG. 3, this EEE control policy may be implemented with at least one component within the EEE control module 318 in the EEE PHY. In one embodiment, a complete EEE control policy may be included in the EEE PHY. In another embodiment, the EEE control policy may be triggered completely by higher layers that may access the traffic profile but do not have real-time control of buffering.

In operation, the EEE control module 318 informs the pause circuit 312 that a pose frame should be generated. For example, the EEE control module 318 can inform the pause circuit 312 that a pause frame should be generated when the EEE control module 318 determines that the EEE PHY will enter a low power consumption mode. As will be appreciated, the decision to switch to or from low power consumption mode may be based on various EEE considerations. In general, EEE control mechanisms can contact many devices and software through the stack and over links. Regardless of the particular EEE control policy mechanism implemented, the EEE control module 318 may generate a trigger for the pause circuit 312 to generate a pause frame for the MAC.

As an example, consider a 10G Ethernet controller that does not provide any hardware support for the low power consumption mode of an EEE enhanced PHY. This transition to the low power consumption mode is in response to a request from the link partner or the device's own EEE control policy (e.g., when the PCIE is in the L1 state, the buffer level reaches a watermark and the rate of change of the traffic queue reaches a threshold). Can be based. As the EEE enhanced PHY initiates the transition to a low power consumption mode, the EEE control module 318 instructs the pause circuit 312 to generate a pause frame to be sent to the 10G Ethernet controller. This pause backpressure mechanism prevents the local MAC from sending any data to the EEE Enhanced PHY. If the EEE Enhancement PHY again escapes low power consumption due to a local control policy or due to a link partner request, the pause timer will go back to a stable state and then set to zero and be ready for transmission.

Reference is made to the flowchart of FIG. 4 to further illustrate the features of the present invention. As shown, the process begins at step 402 where the EEE control policy indicates the need for switching to a low power consumption mode. As can be appreciated, the EEE control policy can be based on the interpretation of various link related parameters or on the end of the link. Regardless of the EEE control policy used, the PHY is changed to the indicated needs for switching to a low power consumption mode.

According to such an indication, in step 404 the EEE control in the EEE PHY signals the power consumption mode switch to the pause circuit in the EEE PHY. Corresponding to such a received signal, in step 406 the pause circuit in the EEE PHY generates a pause frame. In step 408, the EEE PHY sends the generated pause frame upstream to the legacy MAC. If the pause frame is received, at step 410 the legacy MAC suspends transmission of traffic for the EEE PHY that caused the pause frame. This transmission hold will be maintained until the pause timer is released or until a zero pause frame is received. At this point the EEE PHY transitions to a low power consumption mode (eg, LPI or subset PHY mode) at step 412, where the EEE related functions may be initiated. During this low power consumption mode in step 414, the EEE control policy monitors the situation. During this monitoring, the EEE control policy may monitor the release of the pause timer to determine whether it can be released or if another pose should be issued. Moreover, the EEE control policy may determine whether zero poses should be issued to deviate from that state.

As described, EEE control policies can be used to cause the generation of pause frames, thereby leveraging existing backpressure mechanisms in a unique manner. In yet another embodiment, a software mechanism may be used to stimulate receipt of the EEE PHY generated pause frame. In this way, the hardware pause mechanism does not need to be actually triggered to achieve the results affected by the software. In a more detailed embodiment, a PHY without a pause circuit can be used with a software mechanism that causes the receipt of an EEE PHY generated pause frame.

In one embodiment, the EEE PHY generated pause mechanism can be used in conjunction with other mechanisms designed to manage traffic from a MAC that was not fitted by the PHY at that point in time. For example, the principles of the present invention may be used with a MAC or PHY and may be used with other buffering mechanisms designed to absorb traffic directed at the PHY. This additional buffering can be used to absorb traffic generated from typically generated pause frames that are not excluded through the use of pause frames for EEE purposes. Additional buffering can also be used to reduce latency.

In one embodiment, the EEE PHY also includes a buffer on the receive side, as shown in FIG. RX buffer 512 in EEE PHY 510 is generally designed to buffer traffic received from EEE PHY 520. One of the advantages of such RX buffering is that the EEE PHY 520 can send traffic to the EEE PHY 510 when the EEE PHY 510 decides to switch to a low power consumption mode. As described above, this transition occurs with the generation of the pause frame 532 by the local side. In this scenario, the RX buffer 512 is designed to absorb the receiving input, thereby ensuring that the pause frame 532 does not step over any packets coming from the EEE PHY 520 on the remote side. Will be. In one embodiment, the RX buffer 512 is a relatively thin buffer that can absorb receive side traffic while the pause frame 532 (eg, 64 byte packet) is transmitted to the MAC. Note that one way to avoid RX buffering is to wait for Y seconds without seeing anything on RX before exporting the pose.

Another benefit of the inclusion of the RX buffer 532 in the EEE PHY 510 is that the EEE PHY 510 can examine the combining packets from the EEE PHY 520 to determine whether it contains a pause frame. have. This check is advantageous in that the remote side may have a delayed response to the previous burst. This traffic burst can lead the EEE PHY 520 to generate a typical pause frame 534. In general, the pose frame 534 generated by the remote side may have a different value than the pose frame 532 generated by the local side. For example, the pose frame 534 may have a smaller value than the pose frame 532. In another example, the remote side may have an already issued pose frame with a value greater than the pose frame issued by the local side. In such scenarios, the EEE PHY 510 may rewrite the pose value of any pose frame that is intercepted and sent to the MAC to account for other pose frames. By this process, the EEE PHY 510 will track various pose requests.

To accommodate jumbo packets (e.g. 9K) that would exceed a certain size of the RX buffer 512, the EEE PHY 510 will send to the remote side before sending the locally generated pose to the MAC. It should be noted that it may be designed to generate a typical pose to transmit.

As can be appreciated, the principles of the present invention can be used within various PHY / MAC interfaces. For example, the PHY / MAC signaling of the present invention may include Attachment Unit Interface (AUI), media independent interface (MII), serial MII (SMII), reduced MII (RMII), gigabit MMI (GMII), reduced GMII (RGMII), Serial GMII (SGMII), 10 gigabit MII (XGMII), 10-Gbps AUI (XAUI), or such interfaces, out-of-band signaling mechanisms, register-based communication based communication). Additionally, the principles of the present invention may be used with various PHY types (e.g. backplanes, twisted pairs, optical, etc.), as well as standard or non-standard (e.g. 2.5G, 5G, 10G, other) link rates, future link rates. Can be used in combination with, for example, 40G, 100G, etc.

The principles of the present invention can be applied to symmetric or asymmetric applications of EEE. In symmetrical applications of EEE, the bidirectional of the link can be switched between various power consumption modes in a coordinated fashion. In asymmetric applications of EEE, the bidirectional directions of the link can be switched independently between various power consumption modes.

Various aspects of the invention will be apparent to those skilled in the art upon review of the foregoing detailed description. While the detailed features of the invention have been described above, the invention may include other embodiments that may be practiced and performed by various methods apparent to those of ordinary skill in the art after reading the disclosed invention. Therefore, the above description should be considered as not excluding these other embodiments. It is also to be understood that the phraseology and terminology employed herein is for the purpose of description and should not be regarded as limiting.

1 shows an example of a controller.

2 shows an example of a switch.

3 shows an example of generation of a pause frame based on an energy efficient Ethernet PHY with control policy support using PAUSE.

4 shows a process flow diagram of the present invention.

5 shows an example of an energy efficient Ethernet PHY with a receive buffer.

Claims (10)

An energy efficient Ethernet method performed in an energy efficient Ethernet physical layer device coupled to a medium access control device. Detecting, by the physical layer device, a need for a transition of the physical layer device between different power consumption modes; Generating, by the physical layer device, a pause frame in response to the switching between different power consumption modes; And Transmitting, by the physical layer device, the generated pause frame to the medium access control device; The generated pause frame instructs the media access control device to reduce the amount of traffic sent to the physical layer device to be suitable for the switching at the physical layer device. The method of claim 1 wherein the transition is a transition to a low power idle mode. The method according to claim 1, And said transition is a transition to a subset physical layer device mode. The method of claim 1 wherein the physical layer device is a backplane device. The method of claim 1 wherein the physical layer device is a twisted pair device. The method of claim 1 wherein the detecting step comprises monitoring a traffic queue. An energy efficient Ethernet method performed in an enhanced physical layer device coupled to a legacy media access control device. Detecting, by the enhanced physical layer device, a need for a transition of the enhanced physical layer device to a low power consumption mode; And The enhanced physical layer device reducing traffic flow from the legacy media access control device for the enhanced physical layer device in accordance with the detected need, wherein the reducing is supported by the legacy media access control device. An energy efficient Ethernet method comprising signaling using a backpressure control mechanism. 8. The method of claim 7, wherein the signaling comprises transmitting a pause frame. 8. The method of claim 7, wherein said detecting comprises monitoring a traffic queue. An energy efficient Ethernet physical layer device coupled to a media access control device. A control module for generating a control signal in response to a need for switching the physical layer device to a low power consumption mode; And A pause frame coupled to the control module to generate a pause frame in response to the generated control signal, and to reduce the flow of traffic from the medium connection controller to the physical layer device; An energy efficient Ethernet physical layer device comprising a pose generation module for sending to.

Images